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See, I think that your comment is FUD. I think that if these microwaves are at the right frequency to excite water molecules (and thus hurt animals) that they'd also be absorbed by the atmosphere and thus not useful for the transmission of power. But every time this story comes up, someone makes a post based on fear. How sad.

Reasonable people: Let's use this wonderful new technology!Environmentalists: No way! It's dangerous!Reasonable people: Err, no it's not. The technology is based on well-understood principles we've been using for decades.Environmentalists: But how do you know that this particular combination of principles won't cause some damage! You have to prove it. Do you have any evidence that this technology doesn't hurt anything?Reasonable people: Okay, we'll humor you. Let's run an experiment.Environmentalists: No testing! We don't know whether this technology is safe! You might hurt someone or something!

Come on. You should know better. We know what microwaves do at the energy densities indicated. We have absolutely no reason to believe they might cause wide-scale changes to ecosystems. The burden of proof is on you to show that there is actually a harmful effect.

You can tell an environmentalist had mod points because this is modded troll. The fact is though, we *do* understand microwaves pretty damn well. I'd say we understand them better than a lot of other physical phenomena (I'm a physics undergrad). His point about the environmentalists is spot on. It happens all the time: look at nuclear power plants. Chernobyl _could never happen again_, but that's flaunted around by all those do-gooder enviros. And the truth is that we understand nuclear plants pretty damn well, and we build extremely safe ones now. But that's not enough.
The environmentalists hurt the environment more by stifling innnovation than any amount of space power satellites ever would. Hell, more birds die from collisions with planes and high rises, but no one is calling for us to ban those. It's FUD, and it's bullshit. These are the same people that are cheering on wind energy: hate to break it to you, but wind mills are far more dangerous to birds and wildlife than a microwave beam.

Let's not forget PCBs and DDT and Mercury based felt hats and lead paint as all things that were WIDELT beleived to be safe and a boon to mankind until they turned out not to be. Id say the jury is still out on long term problems with cell phones and powerlines. People are only now rethinking the subtle effects of heat islands produced by cities. And there's some concern that the plasticizers in water bottles is now showing up in human organs.

I have done research similar to what you are talking about. I have exposed microwaves to a couple of generations of Homo sapiens. The prolonged exposure has been quite detrimental. Test subjects have shown an increase in weight gain, decreased health and several grotesque genetic mutations. Their diet has even changed from mom's home cooking to TV dinners. The population has changed so drastically, I have dubbed the new species Homo laziens.

First off, directed != broadcast. Doesn't matter? Fine. It doesn't have to. Second off, show me your 200MW bluetooth device. You must have quite some range on that. I'm not an environmentalist, and I like nuclear power (when handled responsibly). With regard to your question about why arguments from the position of ignorance are allowed, I will have to contend by saying that they worked pretty well for this guy [wikipedia.org] until everyone decided he must be forcefully outed and silenced. "Either get on the side of science or get away from a computer"? I draw an interesting parallel, if I don't say so myself. I don't hate science, I don't hate advancement, and I don't hate progress. I hate people who take a stance without considering all the possibilities and leap to conclusions without extensive testing. Do your cell phones and bluetooth earpieces cause cancer? Most studies say no, but after five seconds of google work, I found this [scientificamerican.com] and this [go.com]. Are those real or are they more people "just as stupid as someone arguing against evolution.."? I don't know. Obviously there are contridictory results, so someone has to be wrong. There is an awful lot of money invested in cell phones. Which one is the disinformation coming from? I can't tell because I don't know who to trust.

I hate people who take a stance without considering all the possibilities

All the possibilities huh. There's a difference between rational consideration and the constant cynical sniping that is so common today. We can't suggest *anything* without people leaping over themselves to suggest a doomsday scenario associated with it. Those are the people (and you're in that group) that need to STFU. If there's a scientist or an engineer who says, "wait a minute" then I'll listen. Everyone else is just being attention whores.

Someone proposes wind power. Response:whoa whoa whoa, you haven't considered all the possibilities! Low frequency noise from the blades could cause earthquakes!!

Someone proposes creating an "internet" Response: whoa whoa whoa, you haven't considered all the possibilities! Haven't you read 1984??

GPS. Response: whoa whoa whoa, you haven't considered all the possibilities! Those satelites contain nuclear clocks. NUCLEAR! If they crash, they'll explode and kill all life on earth!

Millions of years ago in Africa: hey, let's get the fuck out of here and move North. Response: whoa whoa whoa, you haven't considered all the possibilities.

All I'm saying is that I'm tired of people like you that think it's your duty to imagine some scary consequence. If there were a few of you, it wouldn't bother me, but you're legion. It pisses me off. Your attitude should be, let's try something new and keep our eyes and minds open to see how it works. Once we have at least one of these stations working, THEN we talk about what it's doing to the environment. If it's bad, we shut it down or work to fix it. Sitting back in your chair criticizing proposals by actual smart people just pisses me off - it's a bit like that scene in Cryptonomicon where the snooty academic says, "how many neighborhoods will be bulldoze to build this information superhighway." The guy thought he was being clever, but actually he was just making a fool of himself. He didn't understand the technology - he should STFU.

Try looking at the energy densities per square millimeter. That 200 MW beam is spread out quite a bit.

Well, spread out a bit until SkyNet get angry, then it's a cannon. At that point we'll see which side sent the governator back in time to authorize this. For all we know, the orbital microwave cannon is the weapon needed to defeat SkyNet early!

Frankly, I find arguemtns that the governator was actually sent back in time by SkyNet exactly as credible as environmentalist concerns that we might hurt one fluffy bunny.

Your math is wrong, you are forgetting that you are dealing with sqare units (the common notation for square units is rather confusing which doesn't help). There are 10000 square centimeters in a square meter and 1000000 square meters in a square kilometer. You also seem to be in a bit of a mess with the units of various figures.

believe cell tower microwaves are similarly non-water exciting, but technicians do NOT stand in front of live ones for fear of losing the ability to reproduce.

"All substances are poisons; there is none which is not a poison. The right dose differentiates a poison...."

Paracelsus had no way of anticipating photons, but they act the same way. Regular old light is harmful if sufficient concentration, and gamma rays are harmless at low enough ones. (Which is why we're not building shields against gamma ray burst

Given how much space there is, and how much matter there is (that is, enough to, at a reasonable density, fill up only a really teensy fraction of the space), it seems unlikely that we could "fill up space" with anything.

And, really, until you've created a Dyson swarm or Dyson bubble, which should keep you occupied a long time, I don't see what your issue is here as far as what to do once you've built out to capacity with space-based solar po

Because you haven't run the numbers on the beam power density. The Microwave beam is wide, because it's trivial and cheap to make a huge ground antenna, and because agriculture can be carried out under the antenna. THe beam power density can be held down to just a few times noon sunlight power, and still deliver plenty of energy.

That way, both airplane and albatross are safe to transit the beam area.

Why do you think that?Just because the shuttle is not going to be around anymore does not mean we have no launch capability.We still have the Falcon 9, Delta IV and Atlas V launch vehicles.Delta IV can launch 23,904 lb to GTO [wikipedia.org] Atlas V can put 28,660 lb into GTO [wikipedia.org]

Just to compare the Shuttle capacity to GTO is only 8,390 lb

On Launches to LEO the Shuttle is still outclassed by Atlas V (53,600 lb to Atlas's 64,860 lb)

First of all, the power being there doesn't mean that you absorb it. We're talking about microwaves (and not the cooking kind). It's not visible light or ultraviolet. You won't notice a thing. You won't get a sunburn.

Second, rectennas are stupidly efficient: 87%. We can barely get to 50% with solar. Furthermore, it's a lot cheaper to build a kilometer of rectenna than a kilometer of solar panels, and you can actually use the land underneath for something useful. And also unlike conventional solar, this thing would work all day and all night, every day of the year.

Don't try this bullshit of 'its perfectly safe nothing can possibly go wrong' because it just makes it obvious you either are full of shit/hiding the truth, or just stupid.

We've lived with radio waves all over the place for over a century. Countless studies have shown that electromagnetic radiation produces no deleterious effects. The burden of proof is on you to come up with repeatable experiments providing evidence for falsifiable claims that radio waves are harmful at the levels proposed.

You're off by a considerable margin there. LEO launch costs are a couple thousand dollars per pound, with GEO launches about ten times that. The weight of a space based system can be considerably less than a ground based system. You don't need heavy mirrors or solar panels, and protective structures needed to hold their own weight, as well as hold up to high winds, storms, sand erosion, and other maintenance issues. You would stretch out very thin, high albedo Mylar fabric over a collapsing frame, with

First, a "few times" noon sunlight power, I think would be pretty brutal. To take you literally, it would be like standing in the sun at noon where the sun is say three times brighter than it is. I'm not a physicist, so feel free to tell me why a three times more power sun at noon wouldn't be a problem for me.

Sunlight has two components that make it uncomfortable or dangerous. First is the infrared, which is the heat energy. Second is the Ultraviolet, which can damage skin cells. Because the energy is not in infrared or UV radiation, you will experience neither of these effects. If you're worried about microwave radiation, remember that this includes the frequencies that make up the WiFi, Bluetooth, and AM/FM radio waves that pass through your body all the time.

Secondly,
Doesn't a "few times" noon sunlight power mean that your getting only a "few times" what you'd be getting from the sun by itself, which isn't all that much. Doesn't sound like your going to deliver the concentrations of power that cities need.

So, I'm inclined not to put too much stake in what you said.

Converting electrical power to and from microwave radiation is an order of magnitude more efficient than solar. Also remember that the solar panels placed in space have a large surface area than the antenna, receive more solar energy per area (due to not having losses due to the ozone layer, etc), and can beam power 24/7. So imagine if the sun was 4x more powerful, and the solar panels were 80% efficient, rather than 20%. Using these (thumbnail estimate) numbers, that makes microwave 16x more efficient per unit area than solar. It becomes even more efficient when you take into account that the sun is not as bright at other times of the day (such as 8AM, or 11PM).

This orbiting solar plant would have to be in a geosynchronous orbit to beam the energy to the antenna. It could not beam power 24/7.

You are correct, this was a slight overstatement.

However, the ammount of time where the satellite is in darkness is significantly less than when a ground based solar panel is in darkness. As well, when not in darkness, the solar energy density is very close to its average maximum, which is significantly more than even the noon-time maxiumum for a ground-based solar. In other words, a solar panel on earth generates less energy at 7PM than at noon (due to light passing through additional atmosphere, and even less if the panel is not aimed), but a satellite produces nearly the same amount of power whenever it is in sunlight.

The earth will occlude the sun for about 20 degrees of its 360 degree rotation at geostationary orbit. So the system will not be in sun for 1 hour, 20 minutes each day. Not 24 hour power (more like 22.7 hour), but still much better than solar. A pumped storage or other facility would still allow nighttime off-peak energy to be used during this "dark" time, or during peak hours.

Except that in space, you don't need to deal with atmospheric attenuation. That increases the effective power output of your solar cells quite a bit, even if their efficiency is the same. 50% (to pick an arbitrary figure) of 500MW is a lot more than 50% of 250MW.

So imagine if the sun was 4x more powerful, and the solar panels were 80% efficient, rather than 20%.

And yes, I am an Electrical Engineer.

The issue is that the best cells in the world are still in the high 30% range...
And yes, I do build satellites for a living, and will certainly not invest my money in this company.

Many ground based photovoltaic cells are not operating at this maximum efficiency. Regardless, microwave power efficiency will always be greater than solar. I only intended the efficiency numbers as a rough estimate.

As a satellite designer you should also recognize that it's the solar power density in space, rather than panel efficiency, that make solar so useful in space. The panels receive more energy from the sun, regardless of how efficiently they convert this energy to electricity. In space, it's about 1300W/m^2, at the equator it's about 1000W/m^2 at noon on a sunny day.

If we want another thumbnail calculation, a square meter solar panel in space gets 1300W 22.7hours a day, making an average power of 1230W. For a panel at the equator on a sunny day, assuming it gets full sun 12 hours a day, its power is only 500W on average. Any practical application (not at the equator, cloudy days, additional shade, etc) will reduce this number farther.

Obviously, the power is more efficient per unit area, both of ground and solar panel. If the costs of the satellite are low enough (to be determined), the beamed energy plant will be much more efficient.

If wifi,bluetooth and am/fm waves are so similar, there must be plenty of energy floating around us. Why can't we just recover that energy?
Power your laptop from your WiFi signal.
Heck, with all the radio stations transmitting around us we should be able to pluck a few dozen frequencies and power the radio itself.

How efficient are these antennas again?

The stray microwave radiation is of a much lower average power. In addition, it is spread across a much larger spectrum, making it difficult to grab all the energy at once.

This plant will send a higher power, focused beam of a single frequency, making it highly efficient. Nokia is working on a system like you describe, though it only gets about 10mW of power currently.

"First, a "few times" noon sunlight power, I think would be pretty brutal."

The OP was talking about transiting the collection area, not camping out there. Also we're talking about microwaves rather than visible/UV from sunlight, you will have to ask someone else what the equivalent energy of 3x noon sunlight in microwave form will do, but the point is we're not simply talking about noon sunlight x3, it's not visible/UV at all.

Either a "few times noon sunlight" is a lot, or it isn't.You can't bash the idea as both "dangerously hot/bright" and "too cold/dark for practical use".

Sun at noon can easily generate temperatures over 40C - if a "few times" that is 2.5 or higher, then you're over boiling point of water.You can harvest that energy using 19th century means - like steam engine.That WOULD be quite dangerous, though. No need to argue there.

If "few times" is lower than 1.5 - those are temperature extremes observed in nature. Gra

Folks like the US military are interested. It's expensive to ship fuel for generators to remote outposts. At those prices for power, SPS are competitive. You also get to remove one logistics vulnerability.

While this kind of power beaming technology is possible, I can't imagine that it's all that efficient. Are we really low enough on other forms of power that there will be enough demand to support this kind of remote endeavor?

For specific kinds of applications, yes, there is demand. DARPA is interested in this, because electronics use, and there fore electricity use, by the military has expanded tremendously, even in remote locations. A diesel generator has to receive a constant supply of fuel. This is very expensive and inconvenient on the top of a mountain in Afghanistan. A solar power receiving station doesn't. The power supply is invulnerable to attack. The receiving station doesn't make constant noise. In such contexts, power delivered at rates an order of magnitude higher than commercial generation is very competitive.

We should build something like the Iraqi Super-cannon. The thing was built out of 70's tech and was slated to deliver stuff to orbit for $600/Kg. We could improve on that with new tech and mass production of the rocket-boosted projectiles. Construction materials for SPS could be packaged to survive the G's of being shot out of a cannon. Even electronic components could be built to survive. The US government has specs for electronic components that can survive 100,000 G. (Yes, one hundred thousand!) That would make SPS much cheaper.

On power: The object of the exercise is to put the solar arrays in space, cut out all the atmospheric attenuation due to air and clouds, and then send the power down using microwaves, on wavelengths that are not significantly attenuated by air and clouds.

On pointing: You've never heard of electronically-steered phased array radar, have you?

On efficiency: When the Jet Propulsion Lab tested microwave power beam technology in the 1960s, between two mountains several miles apart, they were hoping to get 63% transmission efficiency. They actually got over 80%. (I think the number was 88%, but don't quote me.)

The key concept on the efficiency question is that solar power in space is effectively unlimited, when compared with available solar power at ground level, because of atmospheric attenuation of light. (Photographers who shoot outdoors know all about this.) Once you have unlimited power at the head end, you don't really care very much about losses due to beamforming.

My source on this is a talk given by Jerry Pournelle in Austin TX in the late 1970s. His slides included photographs of the actual test apparatus, including one of the lit-up light board at the receiving site.

I'd be concerned with maybe its effects on the weather, maybe global warming.
Also, this could affect radio communications on Earth. Or perhaps not, since it probably would operate off of a different frequency.
Personally I think that geothermal energy is still a method of energy production that has yet to be tapped on a more massive scale. Why put up satellites and beam power back to Earth when we have excellent sources of power here?

My thoughts exactly. Have we really tapped all the energy sources here that are reasonable? Apart from the what if it misses and fries someone question, this project would beam extra energy into Earth's energy system. One system might not have a strong effect but lets not forget the law of conservation of energy here.

Personally I think that geothermal energy is still a method of energy production that has yet to be tapped on a more massive scale.

Strictly speaking, you are correct, geothermal is a method that hasn't been tapped on a massive scale (outside of a few places like Iceland). Problem is, there are issues with induced earthquakes with geothermal. Google Basel Geothermal for an example...

What exactly is the issue with diversifying our efforts? There is no rule that states we can only work on one type of technology at a time. I'm tired of all of this "we shouldn't be doing X before we do Y" crap.

I asked this question of an Environmental Physicist. The answer is that it will *prevent* global warming. The reasoning is this:

Right now, we primarily burn coal to produce energy. This isn't an efficient process at all, putting out about 30% energy and 70% heat. Also, there are all the waste products dumped into the atmosphere associated with burning coal. Meanwhile, beaming the energy back to the Earth will (theoretically) be very, very efficient, as in almost all the energy beamed back will be reclaimed as electricity. Replacing coal with this method would reduce the overall heat by 70%.

So yes, this idea will heat the Earth, but not nearly as much as coal. As far as causing other weather changes, health problems, and electronic problems, those are possibilities that are unknown until they try it. The signal should be directed quite precisely to their receiver on Earth, and with any intelligence, they will have a safety system such that the beam shuts off immediately if the receiver notices a dip in power.

My mirror up there in the sky got dinked by a marble sized piece of green cheese and burned up your crop. But don't worry about green, in paper form, cheese form or your crops because you won't be needing those eyes as you looked up at the unusual shiny bright thingy.

Yesterday a piece of space trash knocked our Microwave Power Plant operating over Oregon off target from its station. Unfortunately, it continued to beam a strong powerful ray of energy down as its sights fell over your Western provinces. We are sorry.

We urge you not to think of it as "a swath of destruction" so much as "a wicked cool tattoo"... I heard Mexico is very jealous.

Williston Lake was a very beautiful lake right up until it evaporated... but look on the bright side--there sure the hell ain't no zebra mussels left in there now!

We're also sorry that instead of shutting it down, we just swung it back over Canada to its power station in Oregon and next time we will totally just stop it before this happens. To make up for it, we'll send you some extra power so your people stop rioting and Mad Maxing.

We've know for long that your education system was in trouble, but we didn't know the situation was so desperate. You might want to get a refresher course in geography, but just FYI, Canada is to the north, not to the south of Oregon. If you needed economic support, you should have asked.

A microwave power transmission of this magnitude will use a broad cross section for the beam, such that a big power station is required to absorb the power. If it was suddenly turned and flipped across several miles in a couple seconds, the total amount of extra energy delivered to anyone or anything would be unnoticeable- and microwaves are not ionizing radiation in any event, so if anything bad were to happen, it would be via heat.
Does the fact that a person would supposedly be able to be on top of th

How much does that compare to the energy needed for getting it up in space, getting routine maintenance & repair up in space, the maintenance & repair itself, and possible decommissioning?

So digging / drilling coal and oil out of the ground, and all the processing, transportation and generation infrastructure involved in fossil fuels cost nothing ?

I think the important point is, *once* the infrastructure for these new renewable energy forms is in place, the power itself comes at zero cost... wind, sun and water costs nothing... and doesn't involve the clean up that say coal, oil or nuclear does.

How to decommission a space based reflector ? Switch the thing off. Done. For extra good measure, fit a booster rocket to it, so we can fire it off into deep space once we're done with it.

A far cry from safely storing materials with a half life of 10,000 years, or getting rid of all the carbon dioxide we've pumped into the atmosphere in the last 150 years dues to coal and oil.

It's expensive like hell, sure, but it would start delivering energy long before it's completed and its goals are way more ambitious than this flying solar panel's! Think no more unrenewable energy, no more CO2, no more pollutants (sulphur, heavy metals etc.) from coal plants, no more soil erosion due to dams, no more gas or oil (yeah, in italy they have plenty of those) power plants. Only a few windfarms and perhaps the French nuclear plants to iron out the energy needs during night time.

I think there are some national security implications inherent in relocating all of Europe's electric power generation capacity to Africa. I hope nobody in Africa minds European armies building bases there to guard their energy sources.

But there wouldn't be such implications if the USA built such a powerplant somewhere in Nevada, Utah or Arizona (or New Mexico, Idaho or... there's plenty of deserts in your country).

Compared to the USA, Europe is pretty fucked, when it comes to free areas with plenty of sunlight. But, EU politicians are sucking enough Arab dick, that the political climate may be somewhat favorable for us to build some plants in Morocco and Egypt, perhaps even Algiers, and with enough sucking, Mauritani

Also, if you think orbital solar is expensive, imagine trying to string HVDC lines across hundreds of miles of shifting sand dunes, then under the Mediterranean sea or across Gibraltar. Then think how expensive it'll be to send people into the middle of one Earth's largest deserts to service all this equipment. It makes space look cheap.

You are wrong about this. The 200MW this space gimmick will produce is a drop in the ocean compared to what terrestrial mega-plants can produce. Besides, we already have oil drilling sites in much less hospitable (both politically as well as environmentally) places, and we have to build thick pipe lines to carry that oil, and the servicing of such infrastructure is way more complex than a solar powerplant of the same energy output. AND in addition to all this, the oil drilling site is temporary - it is exha

The reason is that currently, the western militia there must import lots of fuel to provide electricity. That is EXPENSIVE. VERY EXPENSIVE. Instead, the groups could put up one of these that have say 5-50 MW and then put small collectors on the ground. It would be MUCH cheaper than bringing in the equipment and fuel. In addition, if a base is overrun, it would be easy to prevent enemy (read Al Qaeda) from using the equipment and new equipment would be much lighter, easier to take care of, etc. Also, once several of these were up there, they could be shifted around to help on Emergency locations. For example, helping Hurricanes, tsunami, Chinese EarthQuake, 9/11, etc. The ability to get power into a large disaster area means, LITERALLY life or death. If we put at least one over every major continent, they could be used normally to help a city that already has coal/gas, but then moved ahead of time for when a disaster is heading there way (hurricanes), or a day or two for unseen disasters that happen. Heck, if done right, private space industry should push this private tugs. These can then be used for doing other work (perhaps getting rid of space junk).

The launch costs (Falcon 9 $2500/kg) of satellite solar panels (30W/kg with 15 year lifetime) and basically 0% interest rate (straight line depreciation over 15 years) yields a little over 60 cents per kWh at the satellite. Account for transmission losses and you're talking over $1/kWh at the grid.

They must have some big economies somewhere they aren't talking about to make this profitable.

Satellite in geostable orbit. Receiving station on equator. Receiving station emits guiding signal to satellite, causing satellite to beam power to earth. If the guiding signal is missing, the satellite stops beaming power and starts using that power to adjust it's position. That's how I'd do it.

A bit more subtle: The transmitter is using a phased array, and the locking phase is a reflection of the signal from the ground. This is a completely fail-safe system: It doesn't have a machine that says "reference signal gone": if the reference signal disappears, the beam turns into a glow by the laws of physics, not by any allegedly safe automation. And the beam can *only* be aimed at something with an appropriate reflector, so even a mad scientist cannot redirect the beam to a city.

No, they cause all the transmitters to drift out of phase, so that instead of a coherent beam, you have a wide-angle glow. Transmission is done by a phased-array antenna, as used on most modern radar systems. If these all transmit in a carefully calculated phase relationship, interference directs all the energy into a tight beam. If the phase between the transmitters is random, which it will become if not positively locked to a reference beam, all interference disappears and the energy is dissipated in all directions. All you have to do is ensure that the reference phase is derived not from on board, but from the ground: when the reference beam disappears the transmitters lose phase and the beam broadens into nothing. The transmitters will probably lose lock easily anyway, but you can deliberately unstable if you want. To start the system requires someone on the ground to fire a fairly powerful beam from the target area up to the satellite; to maintain it requires a well-aligned reflector.

A phased-array antenna at 2.45 GHz still has a rather wide beam. I would say that a parabolic reflector has a narrower beam than a phased-array antenna - especially at 2.45 GHz. If this were operating at a higher frequency, then sure, you can get a pretty tight beam, but then you start having other atmospheric absorption problems. Rain would be terrible at just about any higher frequency, not to mention oxygen and nitrogen also start absorbing the higher in frequency you go.

Satellite in geostable orbit. Receiving station on equator. Receiving station emits guiding signal to satellite, causing satellite to beam power to earth. If the guiding signal is missing, the satellite stops beaming power and starts using that power to adjust it's position. That's how I'd do it.

That's nice and all, but how about this: If the beam goes off-target, the satellite cranks the output up to full power, obliterating whatever it happens to be pointed at. This will create a bright column of light visible to cameras at the receiving station. Based on which direction this shaft of annihilation is from the station, the ground station transmits instructions to the satellite of which way to adjust the beam, walking it back onto the target and creating a massive swath of destruction in the process.

If you're talking about attitude of a spacecraft in orbit, then as a matter of fact, there are purely electric systems: magnetic torquers [everything2.com]. Lots of satellites use them, including Hubble.

1. With the horror stories about living near power lines, and cell phone usage, what possibke problems could a massive beam of energy blasting from overhead cause?

As those are all false, it's a non-issue.

2. Terrorist with a simple transmitter causing the beam to come down into a nearby city.

Terrorists with a transmitter with enough power to focus a basically harmless beam into a nearby city instead of, I don't know, just using a bomb to blow shit up are hardly a credible threat. Nice movie plot, though.

3. How to you intend on using a power beam to adjust a satellites position, without blasting random sites on the earth? I doubt you can make manouver as necessary without pointing the beam in all directions.

Physics not your strong point? Don't feel bad, most people aren't physicists. But you should avoid expressing strong opinions about what's physically possible when you lack any understa

Most power generation schemes are *heat engines.* The typical efficiency is less than 40%. Microwave transmission starts at 50% efficiency, and is likely to get better. For the same amount of electric power, you're going to have less waste heat than with coal, nuclear, or natural gas power plants.

All current power generation schemes are using energy that already exists on Earth. This would be bringer extra energy to Earth, increasing the total amount of energy in the Earth system. To be fair, though, unburned coal wouldn't be adding to the temperature of the Earth, even if it is still technically energy.

Based on Wolfram Alpha the Earth gets about 1.3 kW per square meter. with the earth being 6.4*10^6 m radius with find the area facing the sun is pi*r^2 = 1.28*10^14. Multiplied by the power gives 1.67*10^17 W hitting the earth. Now since the power company wants to sell 2*10^8 W of power we can conclude that the extra energy reaching the Earth would be in the region of 0.0000001%.

"Atmospheric heating from microwave loss" is another word for "atmospheric attenuation". The trick is you choose microwave frequencies that are not significantly absorbed by nitrogen, oxygen, and water (dihydrogen monoxide), and that knocks out your atmospheric attenuation problem right there.

This is Physics 102, people.

Your real losses are going to be in beamforming and beam wander. You fix beam wander by using a BIG receiving antenna (which also lets you use low power density in the beam: win-win).

It's not just the lack of night, but not having the atmosphere block out a lot of light before it hits your solar cells.

Sim City was fiction. The microwave beams here aren't concentrated enough to be useful as any sort of weapon, either purposely or accidental. The frequencies choosen need to be transparent to water (since it'll have to cut through a lot of it to get to the surface), and the "beam" is spread over a wide area to make simple rectenna receivers possible.

Still the economics of this are a bit puzzling. In 2008, California used 285 million megawatt-hours [ca.gov] of electricity, so even if this project could generate 200 MW 24x7 that still comes to just 511,000 megawatt-hours per year, or a little under 0.2% of Californian consumption. At a wholesale price of $50 per megawatt-hour [doe.gov], that would earn Solaren about $25 million per year. Even over the fifteen year projected lifespan that comes to just $375 million (actually less if you take inflation into account). Is

That report is heavily biased, and overlooks details like the fact that microwave ovens are rated as such becasue the don't run for extended periods of time.The exposure time from a beamed microwave signal will be for an extended period.It also overlooks the fact that the math doesn't seem to add up.

None of that matter, becasue it is cost prohibitive compared to earth based solution.For the cost of the launch alone, you could build a 200MW Solar thermal plant and have enough money to light cigars with 100 b

"it doesn't involve putting up more floating space junk"You mean besides the discarded booster rockets needed to get such a ridiculously further distance out just so we can deal with the difficulties of an additional gravity well?

"it's surface is always facing the sun"If by "always", you mean half the time - 14 days out of every 28.